Scroll compressors are widely used as compressors in, for example, air-conditioners and refrigerators. They generally include two interleaved spiral scrolls, one of which is moved in relation to the other in a circular path. This movement causes chambers formed between the interleaved scrolls to move from outer ends of the scrolls to the centre of the device. The chambers decrease in volume, thereby compressing the fluid. Among other things, scroll compressors can be more compact and can operate more quietly than other types of compressors.
A scroll expander, or, in other words, a scroll air motor, corresponds to a scroll compressor operating in reverse. A high-pressure fluid, e.g. compressed air, can be provided to the centre of the device to cause one of the scrolls to move in relation to the other. In this way, the scroll expander generates mechanical work from the expansion and the transmission energy of the fluid.
Scroll expanders can have various applications.
For example, US 2003/0029169 A1 describes a micro combined heat and power system including a scroll expander. The system operates with an organic working fluid that circulates in a Rankine-type cycle. The fluid is superheated by a heat source, expanded through an involute spiral wrap (scroll) expander such that the fluid remains superheated through the expander, cooled in a condenser, and pressurized by a pump. Heat exchange loops within the system provide hot water production capability, while a generator is coupled to the scroll expander to generate electrical power.
US 2005/0188689 A1 describes a system for generating back-up electrical power. The system includes a vessel adapted to contain a volume of compressed gas and a valve to release gas from the vessel at a predetermined pressure. A scroll expander is adapted to receive and pass the released gas. An electrical generator is drivingly connected to a rotatable member of the expander to generate a supply of electrical power.